The objectives of this proposal are to study the survival and functional results of amputated limbs which have been replanted, and to correlate microsurgical laboratory investigations in order to improve microsurgical techniques and post-operative management in an effort to upgrade viability and function in difficult replantations. Amputated extremities of various animals, specifically rabbit ears, rat legs, and primate digits will be replanted and we shall attempt to solve the problem of the "no flow" phenomenon which is often seen in severe crushing or avulsing amputations which have been replanted. In addition, we will analyze the difference between partial and complete amputations and study the influence of the intact nerve on the revascularized part. The effect of hemodilution on the "no flow" phenomenon will be studied. The effect of vasodilative agents on revascularized and replanted extremities in the immediate postoperative and long term stages in both animals and humans will be critically evaluated. Monitoring devices incorporating cutaneous thermisters, pH recorders, photo probes and transcutaneous PO2 will all be applied to the above studies. Attempt will be made to improve the viability rate of replants in children by investigating replantation of amputated parts in mature and immature animals and by modifying our operative techniques and postoperative management in clinical replantations of children. Our specifically designed computerized cold hand laboratory will be used to analyze 300 replanted parts with at least a two year follow-up to better define criteria for selection and to correlate type of injury and operative technique with sensibility return, useful function, cold intolerance and overall patient satisfaction. SIGNIFICANCE: We shall attempt to obtain a better understanding of the pathophysiology in failed replantations in difficult revascularizations particularly those in children and the avulsed and crushed injuries, in an attempt to improve the success rate in this group by analyzing the pathophysiology, surgical methods, microsurgical technology and postoperative monitoring.